1. Field of the Invention
Embodiments of the present invention generally relate to an integrated electron beam testing system for glass panel substrates.
2. Description of the Related Art
Active matrix liquid crystal displays (LCDs) are commonly used for applications such as computer and television monitors, cell phone displays, personal digital assistants (PDAs), and an increasing number of other devices. Generally, an active matrix LCD comprises two glass plates having a layer of liquid crystal materials sandwiched therebetween. One of the glass plates typically includes a conductive film disposed thereon. The other glass plate typically includes an array of thin film transistors (TFTS) coupled to an electrical power source. Each TFT may be switched on or off to generate an electrical field between a TFT and the conductive film. The electrical field changes the orientation of the liquid crystal material, creating a pattern on the LCD.
The demand for larger displays, increased production and lower manufacturing costs has created a need for new manufacturing systems that can accommodate larger substrate sizes. Current TFT LCD processing equipment is generally configured to accommodate substrates up to about 1.5xc3x971.8 meters. However, processing equipment configured to accommodate substrate sizes up to and exceeding 1.9xc3x972.2 meters is envisioned in the immediate future. Therefore, the size of the processing equipment as well as the process throughput time is a great concern to TFT LCD manufacturers, both from a financial standpoint and a design standpoint.
For quality control and profitability reasons, TFT LCD manufacturers are increasingly turning toward device testing to monitor and correct defects during processing. Electron beam testing (EBT) can be used to monitor and troubleshoot defects during the manufacturing process, thereby increasing yield and reducing manufacturing costs. In a typical EBT process, TFT response is monitored to provide defect information. For example, EBT can be used to sense TFT voltages in response to a voltage applied across the TFT. Alternatively, a TFT may be driven by an electron beam and the resulting voltage generated by the TFT may be measured.
During testing, each TFT is positioned under an electron beam. This is accomplished by positioning a substrate on a table positioned below the beam and moving the table to sequentially position each TFT on the substrate below the electron beam test device.
As flat panels increase in size, so does the table and associated equipment used for the testing. Larger equipment requires more space, i.e., a larger footprint per processing unit throughput, resulting in a higher cost of ownership. The large size of the equipment also increases the cost of shipping and may, in some cases, restrict the means and locales to which such equipment may be transported.
Therefore, there is a need for a compact testing system for flat panel displays that conserves clean room space and that can reliably position flat panels under an EBT device.
The present invention generally provides an integrated system for testing a substrate using an electron beam. In one aspect, the integrated system includes a transfer chamber having a substrate table disposed therein. The substrate table is capable of moving a substrate within the testing chamber in horizontal and vertical directions. The substrate table includes a first stage moveable in a first dimension, a second stage moveable in a second dimension, and a third stage moveable in a third dimension. Each stage moves independently in its respective dimension. The system further includes a load lock chamber disposed adjacent a first side of the testing chamber, and a prober storage assembly disposed beneath the testing chamber. A prober transfer assembly is disposed adjacent a second side of the testing chamber and arranged to transfer one or more probers between the prober storage assembly and the testing chamber. Further, one or more electron beam testing devices are disposed on an upper surface of the testing chamber.
In another aspect, the integrated electron beam testing system includes a substrate table comprising a first stage moveable horizontally along a X axis, a second stage moveable horizontally along a Y axis, and a third stage moveable vertically along a Z axis. The integrated electron beam testing system also includes a load lock chamber disposed adjacent a first side of the testing chamber, a prober storage assembly disposed beneath the testing chamber, a prober transfer assembly disposed adjacent a second side of the testing chamber, and one or more electron beam testing devices disposed on an upper surface of the testing chamber.
The present invention also provides a method for electron beam testing a substrate within an integrated electron beam test assembly. In one aspect, a substrate to be tested is loaded into a testing chamber having a substrate table disposed therein. The substrate table is capable of moving the substrate within the testing chamber in horizontal and vertical directions. The substrate table comprises a first stage moveable in a first dimension, a second stage moveable in a second dimension, and a third stage moveable in a third dimension, wherein each stage moves independently in its respective dimension. Once the substrate to be tested is loaded in the testing chamber, the third stage elevates to position the substrate in a testing position, and electron beams are transmitted from one or more electron beam testing devices disposed on an upper surface of the testing chamber to test the substrate. The first and second stages move in an X or Y dimension to position discrete portions of the substrate beneath the one or more electron beam testing devices. After testing is complete, the third stage is lowered to transfer the tested substrate on an upper surface of an end effector disposed on the second stage. The end effector having the tested substrate disposed thereon then extends into a load lock chamber disposed adjacent a first side of the testing chamber, and transfers the tested substrate to the load lock chamber. The the end effector then retracts to the testing chamber.